The present invention relates to a lash adjuster.
JP-A-2004-278377 discloses a lash adjuster and a valve apparatus of a background art. The lash adjuster includes a body and a plunger in a cylindrical shape. A pressure chamber is defined between the body and a bottom portion of the plunger inserted into the body by increasing or reducing a volume of the pressure chamber by a working fluid introduced into the pressure chamber. The plunger is moved in an axial direction, and a valve clearance in a valve apparatus of an internal combustion engine is automatically adjusted. A gap between an inner peripheral face of the body and an outer peripheral face of the plunger is constituted by a small clearance for leaking the working fluid from the pressure chamber. When the plunger is moved to a lower side relative to the body and the working fluid in the pressure chamber is compressed, the working fluid in the pressure chamber flows out of the pressure chamber by passing the small clearance, and a total length of the lash adjuster is slightly shortened.
The small clearance is required to be controlled highly accurately in order to ensure a performance of the lash adjuster. However, there is a situation that the control of the gap between the inner peripheral face of the body and the outer peripheral face of the plunger is technically difficult and productivity is poor. Particularly, a further deterioration in the productivity is concerned when it is necessary to further narrow the gap between the inner peripheral face of the body and the outer peripheral face of the plunger by a request for downsizing the lash adjuster.